Photoconductive imaging members with N,N-bis(biarylyl)aniline charge transport polymers

ABSTRACT

A photoconductive imaging member comprised of a photogenerating layer, and a charge transport layer comprised of the N,N-bis(biarylyl)aniline charge transport polymers of the formula ##STR1## wherein A and B are independently selected from bifunctional linkages; Z is alkylenedioxy, arylenedioxy, or substituted derivatives thereof; R and R&#39; are alkyl, aryl, alkoxy, aryloxy, or halogen; x and y are mole fractions wherein x is greater than 0 and the sum of x and y is equal to 1.0; a and b are the numbers 0, 1 or 2; and n represents the number of monomer units.

BACKGROUND OF THE INVENTION

This invention is generally directed to photoconductive imaging membersemploying organic polymers as charge transport components. Morespecifically, the present invention is directed to layered imagingmembers with organic charge transport components selected, for example,from N,N-bis(biarylyl)aniline charge transport polymers. Theaforementioned charge transport polymers possess a number of advantagesincluding excellent charge transport properties; they areenvironmentally safe and non-toxic; and their synthesis easilyexecutable by known synthetic processes. In addition, the chargetransport polymers of the present invention can be utilized as asingle-component transport layer, that is without the presence of aresin binder, in layered imaging devices. Single-component transportlayers provide for long-term device, or imaging member stability in thatthey are devoid of the problem of small molecule crystallizationcommonly associated with the small molecule-in-binder transport layercounterparts. Furthermore, the charge transport polymers illustratedherein enable photoconductive imaging members that can be selected forelectrophotographic imaging and printing processes for an extendednumber of imaging cycles, while substantially avoiding, or minimizingundesirable charge transport molecule crystallization. The imagingmembers of the present invention are especially suitable for imaging andprinting apparatuses wherein liquid developers are selected since, forexample, resin binders may be avoided thereby eliminating the problem ofcharge transport molecule leaching and bleeding when the said imagingmembers are in contact with liquid developers. Moreover, the chargetransport polymers of the present invention possess good solubility incommon organic solvents such as halogenated, especially chlorinatedhydrocarbons, tetrahydrofuran, toluene, xylene, and the like, thuspermitting improved coatability thereof by various processes such asspray, dip, and draw-down coating techniques. In one embodiment of thepresent invention the imaging member is comprised of a supportingsubstrate, a photogenerating layer, and in contact therewith a chargetransport layer comprised of the N,N-bis(biarylyl)aniline chargetransport polymer of the formulas illustrated herein. The chargetransport layer can be located as the top layer of the imaging member,or alternatively it may be situated between the supporting substrate andthe photogenerating layer.

The formation and development of electrostatic latent images on theimaging surfaces of photoconductive materials by electrostatic means iswell known. Numerous different photoconductive members for use inxerography are known such as selenium, alloys of selenium, layeredimaging members comprised of aryl amine charge transport layers,reference U.S. Pat. No. 4,265,990, and imaging members with chargetransport layers comprised of polysilylenes, reference U.S. Pat. No.4,618,551. The disclosures of the aforementioned patents are totallyincorporated herein by reference. However, the layered imaging memberswith transport layers incorporating the N,N-bis(biarylyl)anilinepolymers of the present invention are, for example, economically moreattractive than, for example, the members of the '790 and '551 patentsin respect of material and fabrication costs, and possess the otheradvantages illustrated herein. More specifically, theN,N-bis(biarylyl)aniline charge transport polymers of the presentinvention can be synthesized from readily available inexpensive startingmaterials via known synthetic processes. In terms of photochemicalstability, the charge transport polymers of the present invention aresuperior to polysilylenes, and do not photodegrade when exposed toultraviolet radiations.

There are also known photoreceptor materials comprised of otherinorganic or organic materials wherein the charge carrier generation andcharge carrier transport functions are accomplished by discretecontiguous layers. Additionally, photoreceptor materials are disclosedin the prior art which include an overcoating layer of an electricallyinsulating polymeric material, and in conjunction with this overcoatedtype photoreceptor there have been proposed a number of imaging methods.

Specifically, layered photoresponsive devices, including those comprisedof photogenerating layers and transport layers, are disclosed in U.S.Pat. No. 4,265,990, and overcoated photoresponsive materials containinga hole injecting layer overcoated with a transport layer, followed by anovercoating of a photogenerating layer and a top coating of aninsulating organic resin, reference U.S. Pat. No. 4,251,612. Examples ofgenerating layers disclosed in these patents include trigonal seleniumand vanadyl phthalocyanine, while examples of the charge transport layerthat may be employed are comprised of the aryldiamines as mentionedtherein. The '990 patent is of particular interest in that it discloseslayered photoresponsive imaging members similar to those illustrated inthe present application with the exception that the charge transportingcomponent of the members of the present invention are comprised ofcharge transport polymers of the formulas illustrated herein. Thesemembers can be utilized in electrophotographic methods by, for example,initially charging the member with an electrostatic charge and imagewiseexposing to form an electrostatic latent image which can be subsequentlydeveloped to form a visible image. Other representative patentsdisclosing layered photoresponsive devices include U.S. Pat. Nos.4,115,116; 4,047,949 and 4,081,274.

As a result of a patentability search, there was located (1) U.S. Pat.No. 3,265,496, which discloses triarylamine photoconductive polymersderived from the reaction of functionalyzed vinyl polymers such asiodostyrene with diphenylamine, as described in column 3, lines 19 to 30of the patent. At least three important differences exist between thepolymers of the '496 patent and the polymers of the present invention:(a) the polymers of '496 patent are addition (vinyl) polymers derived bypolymer modification of certain functionalized polymers with appropriatediarylamines; the present invention discloses polycondensation polymerswhich are obtained by polycondensation of appropriate monomers; (b) the'496 patent describes triarylamine polymers in which the triarylaminemoieties are covalently linked to the polymer backbones via a singleC--C bond; in the present invention, the N,N-bis(biarylyl)aniline chargetransport moieties are covalently bonded to the polymer backbones viatwo C--O bonds; and (c) the polymers of the '496 patent are functionallyphotoconductive, whereas the polymers of the present invention arenonphotoconductive; they are employed as hole transport materials inlayered imaging devices; (2) U.S. Pat. No. 4,725,518 which discloses atertiary amine as a charge transport small molecule, see for example theformula when R₁ and R₂ are polyphenyl and R₃ is aryl; U.S. Pat. No.3,767,393 which discloses alkylaminoaromatic photoconductors of theformula as illustrated in column 2(R₁ --N--R₂ --Ar); and (3) 3,567,450;3,658,520; 4,025,341; 4,540,651; 4,606,988 and 4,769,302. These patents(3) disclose the use of aromatic amine compounds either as holetransport small molecules or as photoconductive compositions, and areaccordingly not believed to be similar to the present invention directedto the use of charge transport polymers based onN,N-bis(biarylyl)aniline in layered photoconductive devices.

There is also disclosed in Belgium Patent 763,540 an electrophotographicmember having at least two electrically operative layers, the firstlayer comprising a photoconductive layer which is capable ofphotogenerating charge carriers, and injecting the photogenerated holesinto an active layer containing a transport organic material which issubstantially non-absorbing in the spectral region of intended use, butwhich is active and that allows injection of photogenerating holes fromthe photoconductive layer and allows these holes to be transportedthrough the active layer. The active polymers may be mixed with inactivepolymers or non-polymeric materials. Also, there is disclosed in U.S.Pat. Nos. 4,232,102 and 4,233,383, the disclosures of which are totallyincorporated herein by reference, the selection of sodium carbonatedoped and barium carbonate doped photoresponsive imaging memberscontaining trigonal selenium.

The following patent applications and U.S. patents are mentioned: (1)U.S. Pat. No. 4,818,650 describes layered imaging members with novelpolymeric, hydroxy and alkoxy aryl amines, wherein m is a number ofbetween about 4 and 1,000, reference for example Claims 1 and 2; (2)U.S. Ser. No. 061,247 (now abandoned) and U.S. Ser. No. 07/198,254 U.S.Pat. No. 4,871,634 illustrate imaging members with novel dihydroxyterminated aryl amine small molecules, reference Claims 1 and 2, forexample; (3) U.S. Pat. No. 4,806,444, the disclosure of which is totallyincorporated herein by reference, describes layered imaging members withnovel polycarbonate polymeric aryl amines, reference Claims 1 and 2, forexample; (4) U.S. Pat. No. 4,806,443, the disclosure of which is totallyincorporated herein by reference, illustrates novel polycarbonatepolymeric amines useful in layered imaging members, reference Claims 1and 2, for example; and (5) U.S. Pat. No. 4,801,517, the disclosure ofwhich is totally incorporated herein by reference, which disclosesimaging members with novel polycarbonate aryl amines, reference Claims 1and 2 for example.

In U.S. Pat. No. 4,869,988 and application U.S. Ser. No. 274,160entitled, respectively, PHOTOCONDUCTIVE IMAGING MEMBERS WITHN,N-BIS(BIARYLYL)ANILINE, OR TRIS(BIARYLYL)AMINE CHARGE TRANSPORTINGCOMPONENTS, and PHOTOCONDUCTIVE IMAGING MEMBERS WITH BIARYLYLDIARYLAMINE CHARGE TRANSPORTING COMPONENTS, the disclosures of which aretotally incorporated herein by reference, there are described layeredphotoconductive imaging members with transport layers incorporatingbiarylyl diarylamines, N,N-bis(biarylyl)anilines, andtris(biarylyl)amines as charge transport compounds. In theabove-mentioned patent and application, there are disclosed improvedlayered photoconductive imaging members comprised of a supportingsubstrate, a photogenerating layer optionally dispersed in an inactiveresinous binder, and in contact therewith a charge transport layercomprised of the above-mentioned charge transport compounds, or mixturesthereof dispersed in resinous binders.

Examples of specific charge transporting components disclosed in U.S.Pat. No. 4,869,988 include N,N-bis(4-biphenylyl)- 3,5-dimethoxyaniline(Ia); N,N-bis(4-biphenylyl)-3,5-dimethylaniline (Ib);N,N-bis(4-methyl-4'-biphenylyl)-3-methoxyaniline (Ic);N,N-bis(4-methyl-4'-biphenylyl)-3-chloroaniline (Id);N,N-bis(4-methyl-4'-biphenylyl)-4-ethylaniline (Ie);N,N-bis(4-chloro-4'-biphenylyl)-3-methylaniline (If);N,N-bis(4bromo-4'-biphenylyl)-3,5-dimethoxyaniline (Ig); 4-biphenylylbis(4-ethoxycarbonyl-4'-biphenylyl)amine (IIa); 4-biphenylylbis(4acetoxymethyl-4'-biphenylyl)amine (IIb); 3-biphenylylbis(4-methyl-4'-biphenylyl)amine (IIc); 4-ethoxycarbonyl-4'-biphenylylbis(4-methyl-4'-biphenylyl)amine (IId); and the like.

Examples of specific charge transporting compounds disclosed inapplication U.S. Ser. No. 274,160 include bis(p-tolyl)-4-biphenylylamine(IIa); bis(p-chlorophenyl)-4-biphenylylamine (IIb);N-phenyl-N-(4-biphenylyl)-p-toluidine (IIc);N-(4-biphenylyl)-N-(p-chlorophenyl)-p-toluidine (IId);N-phenyl-N-(4-biphenyl)-p-anisidine (IIe);bis(m-anisyl)-4-biphenylylamine (IIIa); (m-tolyl)-4-biphenylylamine(IIIb); bis(m-chlorophenyl) -4-biphenylylamine (IIIc);N-phenyl-N-(4-biphenylyl)-m-toluidine (IIId);N-phenyl-N-(4-bromo-4'-biphenylyl)-m-toluidine (IVa);diphenyl-4-methyl-4'-biphenylylamine (IVb);N-phenyl-N-(4-ethoxycarbonyl-4'-biphenylyl)-m-toluidine (IVc);N-phenyl-N-(4-methoxy-4'-biphenylyl)--m-toluidine (IVd);N-(m-anisyl)-N-(4-biphenylyl)-p-toluidine (IVe);bis(m-anisyl)-3-biphenylylamine (Va);N-phenyl-N-(4-methyl-3'-biphenylyl)-p-toluidine (Vb);N-phenyl-N-(4-methyl-3'-biphenylyl)-m-anisidine (Vc);bis(m-anisyl)-3-biphenylylamine (Vd);bis(p-tolyl)-4-methyl-3'-biphenylylamine (Ve);N-p-tolyl-N-(4-methoxy-3'-biphenylyl)-m-chloroaniline (Vf), and thelike.

While imaging members with various charge transporting substances,including the aryl amines disclosed in the above patents, are suitablefor their intended purposes, there continues to be a need for improvedimaging members, particularly layered members, which are comprised ofsingle-component transport layers based on charge transport polymers,thereby ensuring the long-term stability of the members. Another needresides in the provision of layered imaging members that are compatiblewith liquid developer compositions. Further, there continues to be aneed for layered imaging members wherein the layers are sufficientlyadhered to one another to allow the continuous use of such members inrepetitive imaging systems. Also, there continues to be a need forimproved layered imaging members whose transport layers are devoid ofthe problems of transport molecule crystallization, bleeding andleaching. Further, there continues to be a need for charge transportingpolymers which are also useful as protective overcoating layers, and asinterface materials for various imaging members. Furthermore there is aneed for charge transport compounds or polymers that are nontoxic, andwherein such members are inert to the users thereof. A further needresides in the provision of novel efficient charge transport polymerswhich are readily accessible synthetically for inexpensive commercialstarting materials.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide layeredphotoresponsive imaging members with many of the advantages indicatedherein.

It is also an important object of the present invention to providenovel, efficient charge transport polymers which can function assingle-component charge transport media, that is where a resin binder isavoided, for layered photoconductive imaging members.

It is yet another object of the present invention to provide improvedlayered photoresponsive imaging members with polymer charge transportlayers in contact with a photogenerating layer, which members aresuitable for use with liquid developers.

In a further object of the present invention there is provided animproved layered photoresponsive imaging member with a photogeneratinglayer situated between a supporting substrate, and a charge transportlayer comprised of the charge transport polymers disclosed herein.

In yet another object of the present invention there is provided animproved photoresponsive imaging member comprised of a chargetransporting polymer layer situated between a supporting substrate and aphotogenerating layer.

In another object of the present invention there are provided imagingand printing methods with the layered imaging members disclosed herein.

Another object of the present invention resides in the provision ofcharge transport polymers which are nontoxic, and inert to the users ofthe devices within which they are incorporated.

A further object of the present invention is to provide improved layeredimaging members which are devoid of the problems of transport moleculecrystallization, bleeding and leaching, enabling their selection, forexample, in imaging apparatuses with liquid developer compositions andwhich members are insensitive to changes in environmental conditionswith the charge transport compounds described herein.

A further object of the present invention is to provide novel efficientcharge transport polymers which are readily accessible by simplesynthetic processes.

A further object of the present invention resides in the provision ofimproved layered imaging members comprised of charge transport polymersdoped with (that is admixed with for example) charge transport smallmolecules enabling such devices to be utilized in high speed copying andprinting processes.

These and other objects of the present invention are accomplished by theprovision of layered imaging members comprised, for example, of aphotogenerating layer and a charge transport layer comprised ofN,N-bis(biarylyl)aniline charge transport polymers. More specifically,the present invention is directed to layered imaging members comprisedof photogenerating layers, and in contact therewith charge transportlayers comprised of the N,N-bis(biarylyl)aniline polymers of Formula Ias illustrated herein.

In one specific embodiment, the present invention is directed to alayered photoconductive imaging member comprised of a supportingsubstrate, a photogenerating layer comprised of organic or inorganic,photoconductive pigments optionally dispersed in an inactive resinousbinder, and in contact therewith a charge transport layer comprised ofan N,N-bis(biarylyl)aniline polymer, copolymer, or mixtures thereofrepresented by Formula I, optionally doped with a suitable chargetransport compound, and/or optionally dispersed in a resin binder suchas a polycarbonate ##STR2## where A is a bifunctional linkage such as--O--, alkyleneoxy with from about 1 to about 20 carbon atoms such as--OCH₂ --, --OCH₂ CH₂ --, OCH₂ CH₂ O-- and the like; B is a bifunctionallinkage such as CO--R"--CO--, --COO--R"--OCO--, --CONH--R"--NHCO--,wherein R" is an alkylene function with from about 1 to about 10 carbonatoms such as methylene, dimethylene, trimethylene,3,3-dimethylpentamethylene, and the like, an arylene function with fromabout 6 to about 24 carbon atoms such as phenylene, phenylene, tolylene,anisylene, biphenylene, and the like, ether, or polyether segments, suchas --CH₂ CH₂ OCH₂ CH₂ --, (CH₂ CH₂ O)₂ CH₂ CH₂ --, --C₆ H₄ OC₆ H₄ -- andthe like; Z is alkylenedioxy, arylenedioxy or substituted derivativethereof with 1 to 24 carbon atoms such as 1,3-trimethylenedioxy,1,4-tetramethylenedioxy, 1,6-hexamethylenedioxy, 1,4-phenylenedioxybis(oxyphenyl)propane, bis(oxyphenyl)methane,bis(oxyphenyl)cyclopropane, and the like; R and R' are substituents suchas alkyl, alkoxy, with 1 to about 25 carbon atoms such as methyl, ethyl,propyl, methoxy, ethoxy, propoxy, aryl, or aryloxy such as phenyl,tolyl, phenoxy, and the like, halogen such as chlorine, bromine, and thelike; x and y are mole fractions with the provision that x is greaterthan 0, y can be 0, and that the sum of x and y is equal to 1.0; a and bare the numbers of 0, 1 or 2; and n is the number of monomer unitsranging preferably from about 10 to about 300 or more.

Examples of alkyl and alkoxy groups as indicated herein include thosewith from 1 carbon atom to about 25 carbon atoms, and preferably from 1carbon atom to about 10 carbon atoms, inclusive of methyl, methoxy,ethyl, ethoxy, propyl, propoxy, butyl, butoxy, pentyl, pentoxy, hexyl,octyl, octoxy, nonyl, nonoxy, decyl, decoxy, pentadecyl, searyl, andother similar substituents. Specific preferred alkyl and alkoxy groupsare methyl, methoxy, ethyl, ethoxy, propyl, propoxy, butyl and butoxy.Aryl includes those groups with, for example, from 6 to about 24 carbonatoms such as phenyl and the like.

Examples of specific charge transporting polymers and copolymersinclude, but are not limited to, those of the following formulas,wherein n is as indicated herein ##STR3## The photoresponsive imagingmembers of the present invention can be prepared by a number of knownmethods, the process parameters and the order of the coating of thelayers being dependent on the member desired. Thus, for example, thephotoresponsive members of the present invention can be prepared byproviding a conductive substrate with an optional charge blocking layerand an optional adhesive layer, and applying thereto a photogeneratinglayer, and overcoating thereon a charge transport layer of theN,N-bis(biarylyl)aniline charge transport polymer illustrated herein,optionally doped with charge transport molecules. The improvedphotoresponsive imaging members of the present invention can befabricated by common known coating techniques such as by dip coating,draw-down coating, or by spray coating process, depending largely on thetype of imaging devices desired. Each coating, however, can be usuallydried, for example, in a convection or forced air oven at a suitabletemperature before a subsequent layer is applied thereto.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 represents a partially schematic cross-sectional view of aphotoresponsive imaging member of the present invention;

FIGS. 2 and 3 represent partially schematic cross-sectional views ofpreferred photoresponsive imaging members of the present invention; and

FIG. 4 represents a partially schematic cross-sectional view of aphotoresponsive imaging member of the present invention wherein thecharge transporting layer is situated between a supporting substrate,and the photogenerating layer.

Illustrated in FIG. 1 is a photoresponsive imaging member of the presentinvention comprising a supporting substrate 3 of a thickness of 50microns to about 5,000 microns, a charge carrier photogenerating layer 5of thickness of 0.5 micron to 5 microns comprised of a photogeneratingpigment 6 optionally dispersed in inactive resinous binder composition7, and a charge transport layer 9 of a thickness of 10 microns to 60microns comprised of N,N-bis(biarylyl)aniline polymers, preferably ofthe Formulas II, III, IV, VIII, X, and XI as illustrated herein as acharge transporting substance 11 optionally doped with a suitable chargetransport molecule 14, such asN,N-bis(4-biphenylyl)-3,5-dimethoxyaniline orN,N-bis(4-biphenylyl)-3,5-dimethylaniline in the amount of 1 percent toabout 20 percent by weight. In an alternative embodiment of the persentinvention, and in further regard to FIG. 1, the charge transportinglayer can be situated between the supporting substrate and thephotogenerating layer.

Illustrated in FIG. 2 is a photoresponsive imaging member of the presentinvention comprised of a 25 micron to about 100 micron thick conductivesupporting substrate 15 of aluminized Mylar, a 0.5 micron to about 5micron thick photogenerating layer 17 comprised of trigonal seleniumphotogenerating pigments 19, optionally dispersed in a resinous binder21 in the amount of 10 percent to about 80 percent by weight, and a 10micron to about 60 micron thick charge transport layer 23, comprised ofthe charge transport polycarbonate 24 of Formula II, the chargetransport polycarbonate (III), the charge transport polyester (IV), thecharge transport copolycarbonate (VIII), the charge transportcopolycarbonate (X), or the charge transport polyurethane (XI)optionally doped with the charge transport molecule 25 such asN,N-bis(4-biphenylyl)-3,5-dimethoxyaniline in the amount of 1 percent toabout 20 percent by weight.

Another photoresponsive imaging member of the present invention,reference FIG. 3, is comprised of a conductive supporting substrate 31of aluminum of a thickness of 50 microns to about 5,000 microns, aphotogenerating layer 33 comprised of amorphous selenium or amorphousselenium alloy, especially selenium arsenic (99.5/0.5) and seleniumtellurium (75/25), of a thickness of 0.1 micron to about 5 microns, anda 10 micron to about 60 micron thick charge transport layer 37 comprisedof charge transport polycarbonate 38 of Formula II, the charge transportpolycarbonate (III), the charge transport polyester (IV), the chargetransport copolycarbonate (VIII), the charge transport copolycarbonate(X), the charge transport polyurethane (XI) optionally doped with thecharge transport molecule 39, such asN,N-bis(4-biphenylyl)-3,5-dimethoxyaniline in the amount of 1 percent toabout 20 percent by weight.

Illustrated in FIG. 4 is another photoresponsive imaging member of thepresent invention comprised of a 25 micron to 100 microns thickconductive supporting substrate 41 of aluminized Mylar, a 10 micron toabout 60 micron thick charge transport layer 47 comprised of a chargetransport polycarbonate 48 of Formula II, the charge transportpolycarbonate (III), the charge transport polyester (IV), the chargetransport copolycarbonate (VIII), or the charge transport copolyurethane(X) optionally doped with 1 percent to about 20 percent by weight of asuitable charge transport molecule 49, such asN,N-bis(4-biphenylyl)-3,5-dimethoxyaniline and a 0.1 micron to about 5micron thick photogenerating layer 50 comprised of vanadylphthalocyanine photogenerating pigments 53 optionally dispersed in apolyester resinous binder 55 in the amount of 10 percent to about 80percent by weight.

The supporting substrate layers, may be opaque or substantiallytransparent and may comprise any suitable material having the requisitemechanical properties. The substrate may comprise a layer of an organicor inorganic material having a conductive surface layer arranged thereonor a conductive material such as, for example, aluminum, chromium,nickel, indium, tin oxide, brass or the like. The substrate may beflexible or rigid and can have any of many different configurations suchas, for example, a plate, a cylindrical drum, a scroll and the like. Thethickness of the substrate layer is dependent on many factors including,for example, the components of the other layers, and the like;generally, however, the substrate is of a thickness of from about 50microns to about 5,000 microns.

Examples of preferred photogenerating layers, especially since theypermit imaging members with a photoresponse of from about 400 to about700 nanometers, for example, include those comprised of knownphotoconductive charge carrier generating materials, such as amorphousselenium alloys, halogen doped amorphous selenium, halogen dopedamorphous selenium alloys, trigonal selenium, mixtures of Groups IA andIIA, elements, selenite and carbonates with trigonal selenium, referenceU.S. Pat. Nos. 4,232,102 and 4,233,283, the disclosures of each of thesepatents being totally incorporated herein by reference, copper, andchlorine doped cadmium sulfide, cadmium selenide and cadmium sulfurselenide and the like. Examples of specific alloys include seleniumarsenic with from about 95 to about 99.8 weight percent selenium;selenium tellurium with from about 70 to about 90 weight percent ofselenium; the aforementioned alloys containing halogens such as chlorinein amounts of from about 100 to about 1,000 parts per million; ternaryalloys, and the like. The thickness of this photogenerating layer isdependent on a number of factors, such as the materials included in theother layers, and the like; generally, however, this layer is of athickness of from about 0.1 micron to about 5 microns, and preferablyfrom about 0.2 microns to about 2 microns, depending on thephotoconductive volume loading, which may vary from about 5 percent toabout 100 percent by weight. Generally, it is desirable to provide thislayer in a thickness which is sufficient to absorb about 90 percent ormore of the incident radiation which is directed upon it in theimagewise exposure step. The maximum thickness of this layer isdependent primarily upon factors such as mechanical considerations, forexample, whether a flexible photoresponsive device is desired. Alsothere may be selected as photogenerators provided the objectives of thepresent invention are achieved, organic components such as squaraines,perylenes, reference for example U.S. Pat. No. 4,587,189, the disclosureof which is totally incorporated herein by reference, metalphthalocyanines, metal free phthalocyanines, vanadyl phthalocyanine,dibromoanthanthrone, and the like.

The transport layer is usually comprised of one of the charge transportpolymers illustrated herein, which may optionally be doped with asuitable charge transport molecules primarily to further enhance thephotosensitivity of the imaging members for very high speed copying andprinting applications. The dopants, examples of which includeN,N-bis(4-biphenylyl)-3,5-dimethoxyaniline,N,N-bis(4-biphenylyl)-3,5-dimethylaniline,N,N-bis(4-methyl-4'-biphenylyl)-3-methoxyaniline,N,N-bis(4-methyl-4'-biphenylyl)-3-chloroaniline,N,N-bis(4-biphenylyl)-p-toluidine, N,N-bis(4-biphenylyl)-m-toluidine,N,N-bis(4-biphenylyl)-3-anisidine, and the like, when selected, may bepresent in an amount of from about 1 to about 50 percent by weight, andpreferably from about 5 percent to about 20 percent by weight. Thethickness of the charge transport layer is, for example, from about 5microns to about 50 microns with the thickness depending predominantlyon the nature of intended applications. In addition, a layer of adhesivematerial located, for example, between the transport layer and thephotogenerating layer to promote adhesion thereof can be utilized. Thislayer may be comprised of known adhesive materials such as polyesterresins, reference 49,000 polyester available from Goodyear ChemicalCompany, polysiloxane, acrylic polymers, and the like. A thickness offrom about 0.001 micron to about 0.1 micron for this layer is generallyemployed for the adhesive layer. Hole blocking layers usually situatedbetween the substrate and the photogenerating layer such as thosederived from polycondensation of aminopropyl trialkoxysilane oraminobutyl trialkoxysilane, such as 3-aminopropyltrimethoxysilane,3-aminopropyltriethoxysilane, or 4-aminobutyltrimethoxysilane mayoptionally be introduced to improve the dark decay characteristics ofthe imaging member. Typically, this layer has a thickness of from about0.001 micron to about 5 microns or more in thickness, depending on theeffectiveness with which this layer prevents the dark injection ofcharge carriers into the photogenerating layer.

The charge transporting N,N-bis(biarylyl)aniline polymers or copolymersof the present invention can be readily synthesized from thecorresponding bifunctionalized monomers such as the correspondingdihydroxy derivatives by polycondensation with suitable bifunctionalreagents. The latter can be selected from the group consisting of diacylhalide such as succinyl chloride, adipoyl chloride or azelaoyl chloride,bishaloformates such as ethylene glycol bischloroformate, propyleneglycol bischloroformate, or diethylene glycol bischloroformate, anddiisocyanates such as hexane diisocyanate, benzene diisocyanate ortoluene diisocyanate. Also, the charge transport copolymers of thepresent invention can be obtained by copolymerization, for example, withsuitable dihydroxy comonomers such as bisphenol A, bisphenol Z, andother similar diols. For the charge transport polyesters andpolycarbonates, the polymerization is conducted in an inert atmosphereat temperatures ranging from about 0° C. to about 40° C., and preferablyfrom 10° C. to about 30° C. in the presence of an excess organic basesuch as triethylamine, and the like. Typically, a slight excess ofbishaloformate or diacyl chloride is employed to compensate for thepropensity of the reagent to undergo hydrolysis, and a 2 to about 10fold excess of the base is utilized. The polycondensation is executed ina suitable solvent such as methylene chloride, ethyl acetate and thelike. For the charge transport polyurethanes, the reaction isaccomplished with or without a catalyst in a suitable solvent such asdimethylsulfoxide, dimethylformamide, and the like, at temperaturesranging from ambient to about 80° C. The catalyst of choice forpolyurethane preparation is di-n-butyltin dilaurate, although othercatalysts such as di-n-butyltin sulfite, tri-n-butyltin acetate, ferricacetyl acetonate, triethylenediamine, triethylamine, and the like, canalso be chosen.

The layered imaging members incorporating the charge transport polymersof the present invention exhibit excellent charge transport properties,and possess very low dark decay characteristics. Also, the chargetransport polymers of the present invention can be utilized as singlecomponent charge transport layers, thereby ensuring the long-termstability of transport layers. Imaging members with single-componenttransport layers are especially suitable for use with liquid developercompositions without the problem of crystallization, bleeding orleaching of transport small molecules. As the transport layer of thepresent invention is transparent to the visible light, all the visibleradiation used in the exposure penetrates to the photogenerating layerwithout noticeable loss. The imaging members of the present inventionpossess good photosensitivity and are generally good photosensitiveimaging devices or members.

The following examples are being supplied to further define specificembodiments of the present invention, it being noted that these examplesare intended to illustrate and not limit the scope of the presentinvention. Also, parts and percentages are by weight unless otherwiseindicated.

EXAMPLE I Synthesis of N,N-Bis(4-biphenylyl)-3,5-Dihydroxyaniline

A mixture of 28.0 grams of 4-iodobiphenyl, 4.1 grams of copper bronzepowder, and 20.0 grams of potassium carbonate in 100 milliliters ofSoltrol 220 was mechanically stirred in a round-bottomed flask under anitrogen atmosphere. The mixture was heated with a heating mantle, andwhen the temperature reached 150° C., 7.65 grams of 3,5-dimethoxyanilinewas added. The reaction mixture was subsequently heated under reflux at220° C., and the progress of the reaction was monitored by thin layerchromatography. After five hours, the reaction mixture was filtered, andthe filtrate was evaporated under reduced pressure to remove Soltrol 220. Purification of the brown residue by column chromatography on silicagel using a mixture of hexane and tetrahydrofuran (1:9) as the eluentafforded a light yellow solid which was recrystallized from isopropanolto afford 11.5 grams of the pure productN,N-bis(biphenylyl)-3,5-dimethoxyaniline, melting point 79° C. to 80° C.

¹ H NMR (CDCl₃), δ(ppm): 3.7 (s, 6H); 6.2 (t, J_(m) =2.0 Hz; 1H); 6.35(d, J_(m) =2.0 Hz; 2H); 7.1 to 7.7 (m, 18H).

Elemental Analysis, Calculated for C₃₂ H₂₇ NO₂ : C, 84.00; H, 5.95; N,3.06. Found: C, 84.11; H, 5.73; N, 3.24.

A mixture of 7.30 grams of N,N-bis(biphenylyl)-3,5-dimethoxyaniline asobtained above, and 14.5 grams of sodium iodide in 30 milliliters ofsulfolane was mechanically stirred and heated under reflux at 120° C. ina round-bottomed flask for 15 minutes. The mixture was then cooled toabout 70° C., and 0.25 milliliter of water was added. This was followedby the addition of 13 milliliters of chlorotrimethylsilane over a periodof 15 minutes. The resulting mixture was heated for another 3.5 hoursbefore pouring carefully into 600 milliliters of cold water withstirring. The crude product was isolated, dried, and purified by columnchromatography on silica gel using a 1:50 mixture of acetone andmethylene chloride as an eluent. The yield of purebis(m-hydroxyphenyl)-4-biphenylylamine was 5.30 grams, melting point,132° C. to 134° C.

¹ H-NMR (CDCl₃), δ(ppm): 4.6 (br s, 2H); 6.05 (t, 1H); 6.2 (d, 2H); 7.1to 7.6 (m, 18H).

Elemental Analysis, Calculated for C₃₀ H₂₃ NO₂ : C, 83.89; H, 5.40; N,3.26. Found: C, 83.55; H, 5.32; N, 4.14.

EXAMPLE II Synthesis of Polycarbonate (II)

3.87 grams of N,N-bis(biphenylyl)-3,5-dihydroxyaniline as obtained inExample I were dissolved in a mixture of 8.0 milliliters of methylenechloride and 3.5 milliliters of triethylamine in a round-bottomed flaskunder a nitrogen atmosphere. The resulting solution was cooled to about15° C., and a solution of 2.15 grams of diethylene glycolbischloroformate in 1.5 milliliters of methylene chloride was addeddropwise over a period of 20 minutes. After addition, the reactionmixture was stirred at room temperature for 4 hours before 2 millilitersof absolute ethanol and 1 milliliter of triethylamine were added. Afterstirring for another 1 hour, the reaction mixture was evaporated todryness under reduced pressure. The residue was dissolved in 50milliliters of methylene chloride, and the solution was washed twicewith saturated aqueous sodium bicarbonate solution and three times withwater. The solution was then dried, and concentrated to about 10milliliters in volume. Precipitation from 500 milliliters of swirlingmethanol at room temperature afforded a white solid polymer. Furtherpurification was accomplished by repeating the aforementionedprecipitation. The yield of pure polycarbonate (II) was 4.55 grams, andits number average molecular weight was 15,500 (relative to polystyrenestandard).

IR (neat film): 1,760 cm⁻¹.

¹ H-NMR (CDCl₃), δ(ppm): 3.75 (br, 4H); 4.35 (br, 4H); 6.7 to 6.9 (m,3H); 7.1 to 7.7 (m, 18H).

EXAMPLE III Synthesis of Polyester (IV)

The preparation of polyester (IV) was accomplished in accordance withthe procedure of Example II except that 2.03 grams of freshly distilledazelaoyl chloride was used instead of diethylene glycolbischloroformate. In addition, the polymerization was effected for 10hours instead of 4 hours. The yield of polyester (IV) was 3.80 grams,and its number average molecular weight was 21,000.

IR (neat film): 1,745 cm⁻¹.

¹ H-NMR (CDCl₃), δ(ppm): 1.3 (br, 6H); 1.7 (br, 4H); 2.5 (t, 4H); 6.7 to6.9 (m, 3H); 7.1 to 7.7 (m, 18H).

EXAMPLE IV Synthesis of Copolycarbonate (X; x=y=0.5)

The preparation of copolycarbonate (X) was executed in accordance withthe procedure of Example II except that a mixture of 1.935 grams ofN,N-bis(biphenylyl)-3,5-dihydroxyaniline and 1.026 grams of2,2-bis(p-hydroxyphenyl)propane was employed in place of 3.87 grams ofN,N-bis(biphenylyl)-3,5-dihydroxyaniline. The yield of copolycarbonate(X) was 3.60 grams, and its number average molecular weight was 18,000.

IR (neat film): 1760 cm⁻¹.

¹ H MNR: 1.7 (s, 3H); 3.7 (br, 4H); 4.3 (br, 4H); 6.7 to 7.7 (m, 14.5H).

EXAMPLE V

A photoresponsive imaging member was prepared by providing an aluminizedMylar substrate in a thickness of 75 microns, followed by applyingthereto with a multiple-clearance film applicator a solution ofN-methyl-3-aminopropyl-trimethoxysilane (from PCR Research Chemicals) inethanol (1:20 volume ratio). This layer, 0.1 micron, was dried for 5minutes at room temperature, and then cured for 10 minutes at 110° C. ina forced air oven. There was then applied to this silane layer asolution of 0.5 percent by weight of 49,000 polyester (Dupont Chemical)in a mixture of methylene chloride and 1,1,2-trichloroethane (4:1 volumeratio) with a multiple-clearance film applicator. The layer was allowedto dry for one minute at room temperature, and 10 minutes at 100° C. ina forced air oven. The resulting adhesive layer had a dry thickness of0.05 micron.

A dispersion of trigonal selenium and poly(N-vinylcarbazole) wasprepared by ball milling 1.6 grams of trigonal selenium and 1.6 grams ofpoly(N-vinylcarbazole) in 14 milliliters each of tetrahydrofuran andtoluene. Thereafter, 10 grams of the resulting slurry was then dilutedwith a solution of 0.25 gram of N,N-bis(biphenylyl)-3,5-dimethoxyanilinein 5 milliliters each of tetrahydrofuran and toluene. A 1.0 micron thickphotogenerator layer was then fabricated by coating the above dispersiononto the adhesive layer on the Mylar substrate with a multiple-clearancefilm applicator, followed by drying in a forced air oven at 135° C. for5 minutes. A solution of 1.0 gram of the above prepared charge transportpolycarbonate (II) in 7 milliliters of methylene chloride was thencoated over the photogenerator layer by means of a multiple-clearancefilm applicator. The resulting member was subsequently dried in a forcedair oven at 130° C. for 30 minutes resulting in a 18 microns thicktransport layer.

The fabricated imaging member was electrically tested by negativelycharging it with a corona, and discharged by exposing to white light ofwavelengths of from 400 to 700 nanometers. Charging was accomplishedwith a single wire corotron in which the wire was contained in agrounded aluminum channel and was strung between two insulating blocks.The acceptance potential of this imaging member after charging, and itsresidual potential after exposure were recorded. The procedure wasrepeated for different exposure energies supplied by a 75 watt Xenon arclamp of incident radiation, and the exposure energy required todischarge the surface potential of the member to half of its originalvalue was determined. This surface potential was measured using a wireloop probe contained in a shielded cylinder, and placed directly abovethe photoreceptor member surface. This loop was capacitively coupled tothe photoreceptor surface so that the voltage of the wire loopcorresponds to the surface potential. Also, the cylinder enclosing thewire loop was connected to the ground.

The above imaging member was negatively charged to a surface potentialof 900 volts, and discharged to a residual potential of 100 volts. Thedark decay of this device was about 30 volts/second. Further, theelectrical properties of the above prepared photoresponsive imagingmember remained essentially unchanged for 1,000 cycles of repeatedcharging and discharging.

EXAMPLE VI

A layered photoresponsive imaging member was fabricated by preparing a0.5 micron thick layer of amorphous selenium on a ball grained aluminumplate of a thickness of 7 mils (175 microns) by conventional vacuumdeposition techniques. Vacuum deposition was accomplished at a vacuum of10⁻⁶ Torr, while the substrate was maintained at about 50° C. A holetransport layer in contact with and on top of the amorphous seleniumlayer was obtained by coating a solution of 1.0 gram of the aboveprepared polycarbonate (II) in 7 milliliters of methylene chloride usinga multiple-clearance film applicator with a wet gap of 8 mils.Thereafter, the resulting imaging device was dried in a forced air ovenat 40° C. for 1 hour to form a 20 microns thick transport layer.Subsequently, the imaging member was cooled to room temperture, followedby electrical testing by repeating the procedure of Example V with theexception that a 450 nanometer monochromatic light was selected forirradiation. Specifically, this imaging member was negatively charged to850 volts and discharged to a residual potential of 80 volts. The darkdecay of this device was 10 volts/second.

EXAMPLE VII

A layered photoresponsive imaging member was prepared by depositing a0.5 micron thick layer of amorphous selenium on a ball grained aluminumplate of a thickness of 7 mils in accordance with the procedure ofExample VI. A hole transport layer in contact with and on top of theamorphous selenium layer was obtained by coating a solution of 1 gram ofthe above prepared copolycarbonate (X) in 10 milliliters of methylenechloride by means of a multiple-clearance film applicator. Thereafter,the resulting device or imaging member was dried in a forced air oven at40° C. for 1 hour to form a 15 microns thick transport layer.Subsequently, the imaging member was cooled to room temperature,followed by electrical testing by repeating the procedure of Example IVwith the exception that a 450 nanometer monochromatic light was selectedfor irradiation. Specifically, this imaging member was negativelycharged to 800 volts and discharged to a residual potential of 90 volts.The electrical performance of this imaging member remained essentiallythe same after 1,000 cycles of repeated charging and discharging.

EXAMPLE VIII

A photoresponsive device was prepared by coating a solution of 1milliliter of 3-aminopropyltrimethoxysilane in 100 milliliters ofethanol onto a ball grained aluminum substrate. The coating was heatedat 110° C. for 10 minutes resulting in the formation of a 0.1 micronthick polysilane layer. A dispersion of a photogenerator prepared byball milling a mixture of 0.075 gram of vanadyl phthalocyanine pigmentand 0.13 gram of Vitel PE-200 polyester (Goodyear) in 12 milliliters ofmethylene chloride for 24 hours was then coated on top of the polysilanelayer. After drying the coating in a forced air oven at 135° C. for 6minutes, a 0.5 micron thick phthalocyanine photogenerating layer wasobtained.

A solution for the transport layer was prepared by dissolving 1.0 gramof the above prepared polycarbonate (II) in 8 milliliters of methylenechloride. This solution was then coated over the above photogeneratorlayer using a multiple-clearance film applicator. The resulting devicewas dried in a forced air oven at 135° C. for 30 minutes resulting in a19 microns thick transport layer.

Electrical testing was carried out by repeating the procedure of ExampleV. Specifically, the above prepared imaging member was chargednegatively to 950 volts and discharged with 830 nanometer monochromaticlight to a residual potential of 70 volts. For this imaging device, thedark decay was less than 40 volts/second.

EXAMPLE IX

A layered photoresponsive imaging member with a transport layer of theabove prepared polycarbonate (II) doped withN,N-bis(biphenylyl)-3,5-dimethoxyaniline, and a trigonal seleniumphotogenerator was prepared as follows:

An aluminized Mylar substrate of a thickness of 75 microns with a silanecharge blocking layer, an adhesive layer, and a trigonal seleniumphotogenerating layer was prepared in accordance with the procedure ofExample V. A solution for the hole transport layer was then prepared bydissolving 0.10 gram of N,N-bis(biphenylyl)-3,5-dimethoxyaniline and 1.0gram of the above prepared polycarbonate (II) in 10 milliliters ofmethylene chloride. This solution was then coated over thephotogenerator layer by means of a multiple-clearance film applicator.The resulting member was dried in a forced air oven at 130° C. for 30minutes resulting in a 25 microns thick transport layer.

Electrical testing of the above prepared imaging member was thenaccomplished by repeating the procedure of Example V. Specifically, thisimaging member was negatively charged to 1,100 volts and exposed towhite light of wavelengths of 400 to 700 nanometers. The dark decay wasless than 45 volts/second, and the device was discharged to about 50volts. The electrical properties of this device remained substantiallythe same after 1,000 cycles of repeated charging and discharging.

Although the invention has been described with reference to specificpreferred embodiments, it is not intended to be limited thereto, ratherthose skilled in the art will recognize variations and modifications maybe made therein which are within the spirit of the invention and withinthe scope of the following claims.

What is claimed is:
 1. A photoconductive imaging member comprised of aphotogenerating layer, and a charge transport layer comprised of theN,N-bis(biarylyl)aniline charge transport polymers of the formula##STR4## wherein A and B are independently selected from bifunctionallinkages; Z is alkylenedioxy, arylenedioxy, or substituted derivativesthereof; R and R' are alkyl, aryl, alkoxy, aryloxy, or halogen; x and yare mole fractions wherein x is greater than 0 and the sum of x and y isequal to 1.0; a and b are the numbers 0, 1 or 2; and n represents thenumber of monomer units.
 2. A photoconductive imaging member inaccordance with claim 1 wherein A is --O--, and B is --COO--R"--OCO--,wherein R" is alkylene, arylene, ether, or a polyether segment.
 3. Aphotoconductive imaging member in accordance with claim 1 wherein A is--O--, and B is --CO--R"--CO--, wherein R" is alkylene, arylene, ether,or a polyether segment.
 4. A photoconductive imaging member inaccordance with claim 1 wherein A is --O--, and B is --CONH--R"--NHCO--,wherein R" is alkylene, arylene, ether, or polyether segment.
 5. Aphotoconductive imaging member in accordance with claim 1 wherein y is 0(zero).
 6. A photoconductive imaging member in accordance with claim 1wherein x is a mole fraction number of from 0.1 to about 1.0.
 7. Aphotoconductive imaging member in accordance with claim 1 wherein y is 0(zero).
 8. A photoconductive imaging member in accordance with claim 1wherein the charge transport layer is comprised of the polycarbonate(II), the polycarbonate (III), the polycarbonate (V), the polycarbonate(VI), the copolycarbonate (VIII), the copolycarbonate (X), the polyester(IV), the polyester (VII), the polyurethane (IX), or the polyurethane(XI), wherein n represents the number of monomer units.
 9. Aphotoconductive imaging member in accordance with claim 1 wherein R andR' are aryl of from 6 to about 24 carbon atoms.
 10. A photoconductiveimaging member in accordance with claim 1 wherein R and R' are alkyl offrom 1 to about 20 carbon atoms.
 11. A photoconductive imaging member inaccordance with claim 1 wherein R and R' are alkoxy functions of from 1to about 20 carbon atoms, or halogen.
 12. A photoconductive imagingmember in accordance with claim 1 wherein a and b are equal to 0 (zero).13. A photoconductive imaging member in accordance with claim 1 whereinR or R' is methyl or methoxy groups.
 14. A photoconductive imagingmember in accordance with claim 1 wherein n is from about 10 to about350.
 15. A photoconductive imaging member in accordance with claim 1wherein x is
 1. 16. A photoconductive imaging member in accordance withclaim 1 containing a supporting substrate.
 17. A photoconductive imagingmember in accordance with claim 1 wherein the photogenerating layer iscomprised of inorganic, or organic photoconductive pigments.
 18. Aphotoconductive imaging member in accordance with claim 17 wherein thephotogenerating layer is comprised of selenium, selenium alloys,trigonal selenium, a vanadyl phthalocyanine, squaraine, perylene, metalfree phthalocyanines, metal phthalocyanines, or dibromoanthanthronephotoconductive pigments.
 19. A photoconductive imaging member inaccordance with claim 1 wherein the photogenerating layer is situatedbetween a supporting substrate and the charge transport layer.
 20. Aphotoconductive imaging member in accordance with claim 1 wherein thecharge transport layer is situated between the photogenerating layer andthe supporting substrate.
 21. A photoconductive imaging member inaccordance with claim 19 wherein the supporting substrate is comprisedof a conductive component on an organic polymeric composition.
 22. Aphotoconductive imaging member in accordance with claim 1 wherein thephotogenerating pigments are dispersed in a resinous binder in an amountof from about 5 percent by weight to about 95 percent by weight.
 23. Aphotoconductive imaging member in accordance with claim 22 wherein theresinous binder is a polyester, polyvinyl butyral, a polycarbonate, orpolyvinyl formal.
 24. A photoconductive imaging member in accordancewith claim 1 containing a metal oxide charge blocking layer and anadhesive layer.
 25. A photoconductive imaging member in accordance withclaim 1 containing a polysilane charge blocking layer and an adhesivelayer.
 26. A photoconductive imaging member in accordance with claim 1wherein the polymer charge transport layer is doped with a holetransport molecule in an amount of from about 1 percent by weight toabout 20 percent by weight.
 27. A method of imaging which comprisesgenerating an electrostatic image on the imaging member of claim 1,subsequently transferring this image to a suitable substrate; andthereafter permanently affixing the image thereto.
 28. A method ofimaging which comprises generating an electrostatic image on the imagingmember of claim 8; subsequently transferring this image to a suitablesubstrate; and thereafter permanently affixing the image thereto.
 29. Apolymer in accordance with claim 28 comprised of the polycarbonate (II),the polycarbonate (III), the polycarbonate (V), the polycarbonate (VI),the copolycarbonate (VIII), the copolycarbonate (X), the polyester (IV),the polyester (VII), the polyurethane (IX), and the polyurethane (XI),wherein n represents the number of monomer units.
 30. A polymer inaccordance with claim 28 wherein n is a number of from 10 to about 350.